The reason why it didn't work is because the Accord got under the Crown Vic and lifted the rear tires off the ground(thanks in part to the long rear end of the Crown Vic and probably braking too; where the weight transfer would lift the rear end up anyways); not because it's big in general.

PIT stands for Pursuit Intervention Technique. It doesn't have to be from the side of the vehicle like it is most often done. As long as the vehicle loses control from a contact in the back of the vehicle, it is still considered a PIT.